Method of forming a three-dimensional microstructure on a surface, uses thereof, and microstructured products so obtained

ABSTRACT

A method of forming a three-dimensional microstructure on a flat surface of a support, comprising the application of a first flat and uniform layer of silicone on said surface of support and the application on the first layer of silicone of a second three dimensionally microstructured layer of silicone, said first layer and second layer of silicone become integrally connected to thus form a common three-dimensional microstructure ensuring anti-adhesive properties distributed regularly on the surface of the support, so that any flexible surface of substrate, in particular a surface of adhesive deposited on said layers of silicone will be microstructured by inverse replication of the three-dimensional microstructure formed by the two layers of silicone, where said layers of silicone are fixed by hardening by heating or by exposure to an ultraviolet or electronic radiation, or a combination thereof, applications thereof and films, notably self-adhesive films, such as those microstructured by said method.

The present invention relates to a method of forming a three-dimensionalmicrostructure on a flat surface of a support, to the uses of saidmethod, as well as to the products and in particular to theself-adhesive films comprising such a three-dimensionallymicrostructured surface.

It is known to provide films made of adhesive which are sensitive topressure, and whose topography is conferred by contacting the threedimensionally microstructured surface of a peelable protecting coatingas support, which is essentially the inverse of the three-dimensionalmicrostructure with which the surface of adhesive is contacted, andmethods for the formation of such self-adhesive films. According tothese methods, the three-dimensional structures are obtained either bymechanically embossing the support comprising a flat film made ofsilicone or by coating silicone on a support which already presents amicrostructured surface, in that case matching the topography of thesupport. Although the methods for the formation of such self-adhesivefilms generally turn out to be rather satisfactory, they have limitedapplication, as they can only be produced on expensive polyethylene orpolypropylene supports. In the case of polyethylene and siliconesupports, the formation of microstructures in the silicone is carriedout by hot embossing at speeds on the order of 0.9 m/min of the engravedcylinder which is used for this purpose, which considerably slows theproductivity and raises the production costs of the finished products.

Various articles and other pressure sensitive microstructured adhesivematerials or films are disclosed by patent publications e.g. EP 149135discloses pressure sensitive adhesive structures having islands ofadhesive, EP 180598 discloses removable label stock having adhesivesegments, and EP 861307 discloses an adhesive sheet having a pluralityof adhesive pegs and also it should be mentioned patent application WO97/43319 relating to top coat film useable in preparing a stablepolymeric laminated data carrying device, said topcoat film comprising atopcoat layer being formed from a composition comprising a polymerizablecomposition and a polymeric binder, which is substantially plasticizerfree, and wherein the ratio by weight of polymerizable composition topolymeric binder is between 0.75:1 and 1.50:1 inclusive. U.S. Pat. No.4,986,496 relates to an article capable of reducing the resistance todrag of a fluid flowing thereover, which comprises a thermoset polymericsheet formed in situ from the reaction product of an isocyanate with apolyol, said sheet having a surface contacting said fluid comprising aseries of parallel peaks separated from one another by a series ofparallel valleys. Patent application EP 0 382 420 A2 provides acomposite plastic article comprising a tough, flexible substrate, oneface of which bears a microstructure of discontinuities, whichmicrostructure has a depth of 0.025 mm to about 0.5 mm, and comprises acured oligomeric resin having hard segments and soft segments, the curedresin being substantially confined to the microstructure portion of thecomposite.

One of the purposes of the present invention, consequently, consists inovercoming the above-mentioned drawbacks and in providing a method offorming a three-dimensional microstructure on a flat surface of asupport which wholly differs from the known processes consisting indeforming a previous plane surface, presiliconized or not to get thedesired final microstructured surface.

For this purpose, according to the present invention, theabove-mentioned method of making a three-dimensional microstructurecomprises the application of a first flat and uniform layer of siliconeon said surface of support and the application on the first layer ofsilicone of a second three dimensionally microstructured layer ofsilicone, said first layer and second layer of silicone becameintegrally connected to thus form a common three-dimensionalmicrostructure ensuring anti-adhesive properties distributed regularlyon the surface of the support, so that any flexible surface ofsubstrate, in particular a surface of adhesive deposited on said layersof silicone will be microstructured by inverse replication of thethree-dimensional microstructure formed by the two layers of silicone,said layers of silicone being fixed by hardening by heating or byexposure to an ultraviolet or electronic radiation, or a combinationthereof.

Another purpose of the present invention consists in providing a methodfor three-dimensional microstructuring of a surface made of a flexiblesubstrate, in particular a surface of adhesive, which can be produced onany type of substrate, such as papers, plastic films or others, andwhich allows one to work at very high speed, thus increasing theproductivity considerably compared to the known prior methods.

For this purpose, according to the present invention, theabove-mentioned three-dimensional microstructuring method comprises theapplication of a first layer of silicone, which is substantially flatand uniform, on a surface of a support, the application on the firstlayer of silicone of a second three dimensionally microstructured layerof silicone, where said first and second layers of silicone becomeintegrally connected thus forming a common three-dimensionalmicrostructure ensuring anti-adhesive properties which are distributedevenly over the surface of the support, and the deposition of theflexible surface of substrate, in particular of the surface of adhesive,on the above-mentioned layers of silicone in such a manner that saidsurface made of flexible substrate, in particular of adhesive, ismicrostructured by inverse replication of the common three-dimensionalmicrostructure formed by the first layer of silicone and the secondlayer of silicone, where said layers of silicone are fixed by hardeningby heating or by exposure to an ultraviolet or electronic radiation, ora combination thereof.

Advantageously, the first layer of silicone comprises at least onefunctionalized polyorganosiloxane with groups

as crosslinking agent, and at least one functionalizedpolyorganosiloxane which can react with the crosslinking agent, or itcomprises a functionalized polyorganosiloxanes with groups

as crosslinking agent, and at least one functionalizedpolyorganosiloxane with groups

which can react with the crosslinking agent, where R comprises at leastone ethylenic unsaturation, and optionally, in one or the other case, anactivation catalyst for the above-mentioned crosslinking reaction, andit is hardened by heating or by exposure to ultraviolet or electronicradiation.

According to an advantageous embodiment of the invention, theabove-mentioned second layer of silicone comprises at least apolyorganosiloxane and, advantageously, a polydimethylsiloxane withacrylate and/or epoxy function, and optionally an activation catalyst.

According to another advantageous embodiment of the invention, thesecond layer of silicone comprises a polydimethylsiloxane with acrylatefunction and a catalyst of the ketone type, advantageously of thebenzophenone type, or it comprises a polydimethylsiloxane with epoxyfunction and a catalyst of the iodonium salt type, and it is hardened byexposure to ultraviolet radiation.

According to yet another advantageous embodiment, the second layer ofsilicone comprises no activation catalyst and it is hardened by exposureto electronic radiation.

The invention also concerns the three dimensionally microstructuredfilms, and the self-adhesive films which comprise a surface such as onewhich has been three dimensionally microstructured by theabove-mentioned method, notably one comprising motifs which can be usedfor decorative, publicity or other purposes, notably on the surfaceopposite the adhesive surface of the self-adhesive films.

As already indicated above, to form a three-dimensional microstructureon a flat surface of a support, such as a flexible support like paper ora plastic film, one applies a first layer of silicone substantially flatand uniform on said surface of support and one applies on the firstlayer of silicone a second layer of silicone which has been threedimensionally structured, in such a manner that these layers of siliconebecome integrally connected to thus form a common three-dimensionalmicrostructure ensuring anti-adhesive properties on the surface of thesupport. Thus any flexible surface of substrate, in particular anysurface of adhesive, deposited on both the integrally connected layersof silicone will be microstructured by inverse replication of thethree-dimensional microstructure formed by the latter.

According to a particularly preferred embodiment of the invention, toconfer a three-dimensional microstructure to a flexible surface ofsubstrate, and in particular to a surface of adhesive, one applies acontinuous first layer of silicone which is substantially flat anduniform on a surface of a support, such as one made of paper, which may,for example, be calendered or sized, or a plastic film, such as one madeof polyethylene, polyester, polypropylene, polyvinyl chloride, polyamideor a similar material, and one applies to the first layer of silicone asecond layer of silicone which has been three dimensionally structured,in such a manner as further described below that these layers ofsilicone become integrally connected to thus form a commonthree-dimensional microstructure ensuring anti-adhesive properties whichare distributed evenly on the surface of the support. Then, one depositsby means well known in the art. e.g. by coating and/or lamination theflexible surface of substrate, or, in particular, the above-mentionedsurface of adhesive, on the layers of silicone in such a manner thatsaid surface of substrate, in particular of adhesive, is microstructuredby inverse replication of the common three-dimensional microstructureformed by the first and the second layer of silicone. In this regard,the expression “microstructured by inverse replication” refers to thefact that the topography obtained on the surface of the flexiblesubstrate, in particular of the adhesive, is the inverse motif of thesurface topography formed by the combination of the first layer and thesecond layer of silicone, whose three dimensions in space aresubstantially similar or similar to the latter.

Throughout the present description as well as in the claims, the term“substrate” denotes any product which will be microstructured by inversereplication of the microstructure formed by the combination of the firstlayer of silicone and the second layer of silicone and the term“support” will denote any product to which the first layer of siliconeor layer of silicone which is substantially flat and uniform is applied.

The first substantially flat and uniform layer of silicone is formedfrom a composition of silicone which is based on one or morefunctionalized polyorganosiloxanes (POS) with groups

as crosslinking agent, and from one or more functionalizedpolyorganosiloxanes (base resin) which can react with the crosslinkingagent by polycondensation in the presence of a solvent, and preferablyof a tin based activation catalyst, except in the case of hardening ofthe layer by exposure to electronic radiation. In a variant, one coulduse as base resin one or more functionalized polyorganosiloxanes withgroups

which can react with a crosslinking agent by polyaddition with orwithout solvent, where R comprises at least one ethylenic unsaturation,preferably a vinylic unsaturation, in the presence of platinum and/orrhodium catalyst.

This composition of silicone moreover can comprise additives such asthose which are conventionally used in this type of application, namelyan adhesion modulator, for example, based on a silicone resin comprisingsiloxyl units, reaction accelerators and inhibitors, pigments,surfactants, fillers or similar substances. To facilitate theapplication of the layer of silicone, the composition of siliconementioned above can be liquid and diluted in a solvent such as hexane ortoluene and, for reasons pertaining to hygiene and safety, it can be inthe form of an aqueous dispersion/emulsion. The expression “flat anduniform” denotes the fact that the layer of silicone comprises nosurface asperities or roughness which could tarnish the flatconfiguration of its surface, i.e. the silicone layer will tend to wetout and be continuous over a support surface without having anydisruptions that would interfere with the ultimately desired releasecharacteristics or 3 dimensional topography of the siliconized supportfollowing the application of the second layer. This composition ofsilicone constituting the first layer, which is either made of a solventbase or without solvent, is hardened by crosslinking with heating in areaction of polyaddition or polycondensation, for example, by beingsubjected to temperatures of 70-220° C., advantageously 100-180° C., orunder exposure to radiation energy, such as ultraviolet or electronicradiation. In the case of a thermal treatment, the layer of silicone canbe hardened by passing the support to which it is applied throughthermal ovens whose temperature can vary from 100-220° C., with aresidence time in the thermal oven which can range from 2 sec to oneminute. The coating rate is generally determined by the temperatureprofile in the ovens and by the length of the ovens. In the case of atreatment under radiation energy, the silicone layer is brought into aUV oven or an oven with electronic radiation and it is hardened nearlyinstantaneously; however, the composition of silicone of the radical orcationic type does not require the presence of a catalyst duringexposure to an electronic radiation. The flat layer of silicone may havea thickness of 0.4-1.6 μm, advantageously 0.7-1.2 μm. This siliconelayer, in general, is applied with a five-roller system for thecompositions without solvent and with a system of the type with coatingroller and Mayer doctor bar for the compositions with a solvent oraqueous base. Thicker or thinner first layers of silicone may be used ifdesired. However, thicker layers have a greater material expense, andthinner layers may require greater care in formation to avoidundesirable disruptions in coverage over the support. It will beappreciated that the first layer of silicone itself may be built up byapplication of multiple coats of silicone and that the formulation ofeach coat may vary, however for ease of manufacture a single coat may beapplied.

According to the present invention, the second layer of silicone orthree dimensionally microstructured layer of silicone is formed from acomposition of silicone comprising one or more polyorganosiloxanes and,advantageously, one or more polydimethylsiloxanes with acrylate and/orepoxy function, and optionally an activation catalyst as a function ofneed. This composition of silicone is without solvent and it is hardenedeither by exposure to ultraviolet radiation (polydimethylsiloxane withacrylate and/or epoxy function) or by exposure to electronic radiation(polydimethylsiloxane with acrylate function), in which case it does notrequire the presence of an activation catalyst. A suitable UV dose toensure a correct crosslinking of the silicone is generally greater than700 mJ/cm². When the composition of silicone comprises one or morepolydimethylsiloxanes with acrylate function, and the microstructuredlayer of silicone is hardened by UV radiation (radical system), one mayuse, as catalyst, a ketone photoinitiator, advantageously of thebenzophenone type, a specific example being2-hydroxy-2-methyl-1-phenylpropanone. To optimize the adhesion of themicrostructured layer to the first silicone layer, one can incorporatean adhesion agent such as polydimethylsiloxane dipropoxylated diglycidylether. In the case where the composition of silicone comprises one ormore polydimethylsiloxanes with epoxy function one uses, as catalyst, aphotoinitiator of the iodonium type such as diaryliodonium tetrakis(pentafluorophenyl) borate or iodonium hexafluoroantimonate (cationicsystem). In general, the radical systems are preferred over the cationicsystems, because they possess a better stability of the anti-adhesive(substrate release) properties over time while, however, requiring thepresence of a system for rendering inert with nitrogen during thecrosslinking reaction to lower the oxygen level in the gas atmosphere toless than 50 ppm. Like the first layer of silicone, the composition ofsilicone used to form the second microstructured layer can contain otheradditives, such as fillers, accelerators, inhibitors, pigments andsurfactants. The coating of the microstructured layer of silicone isgenerally carried out using an engraved cylinder. Suitable coatingspeeds of 10-600 m/min may be used. The quantity of silicone(polydimethylsiloxane) will vary as a function of the engraving of thecylinder, the viscosity of the composition, the viscosity of theaddition products which can modify the rheological behavior of the layerof silicone, and as a function of the temperature of the silicone. Infact, the silicone is transferred from a roller which is engraved ontothe surface of the first layer of silicone to be coated. The engravingof the engraved cylinder is filled by immersion into an ink fountain orreceptacle containing silicone. The excess silicone is generallyeliminated by means of a doctor bar. A rubber counter roller will beused to ensure the correct transfer of the layer of silicone. Theengraving of the cylinder will determine the topography of the layer ofsilicone, that is the desired three-dimensional microstructure. Thequantity of silicone deposited may be controlled and can vary e.g. from3 to 25 g/m², advantageously from 4 to 15 g/m². The three-dimensionalmicrostructure formed by the combination of the first layer and thesecond layer of silicone advantageously consists of microstructuredunits, for example, micro-honeycombed, ridged, or grid shaped motifs,whose crest height can be predetermined. Beneficially, crest heights of3-50 μm, advantageously 5-25 μm, may be used. For example, the engravingused can present the following characteristics: shape: truncatedpyramidal, depth (height): 50 μm, opening: 100 μm, diagonal measurementof the pyramid: 500 μm, theoretical volume: 15 cm³/m². Themicrostructured layer of silicone which is applied to the flat surfaceof the first layer of silicone should be crosslinked as rapidly aspossible e.g. by UV radiation or electron beam, and thus, in the case oftreatment by UV, the UV lamps are positioned preferably as close aspossible to the siliconization station (where the second layer isapplied to the first layer). The power of the UV lamps can range from120 W/cm to 240 W/cm or more, and it may determine the speed of coatingof the microstructured silicone (approximately 100 m/min at 120 W/cm maybe achieved). During the coating of the microstructured silicone withthe help of a special engraved cylinder (so-called “inverse or negative”engraving) on the flat layer of silicone, the latter must be depositedfirst on the support e.g. of paper or plastic, or during a separatecoating (presiliconization process), or in tandem, that is on themachine which is in the process of coating the microstructured layer ofsilicone. The coating of the microstructured layer of silicone can alsobe carried out using a rotating sieve, in which case the silicone ispassed through the sieve in contact with the surface to be coated of thefirst layer. For example, the sieve which is used can have the followingcharacteristics: a 30 mesh sieve; thickness of 200 μm, 15% of openingsurface, dimension of the holes of 345 μm, theoretical volume of thefluid of silicone passing through: 30 cm³/m². These parameters areexemplary and may be varied as desired. It is not recommended tocrosslink the microstructured layer by the thermal route, because thetemperature required for the crosslinking would destroy itsthree-dimensional structure as a result of flowage even before it can befixed by crosslinking. In addition, another drawback from the point ofview of the resistance of the spatial structure of the motif during itscoating would be that the viscosity of a composition of silicone whichhas been treated by the thermal route would be on the order of 200400mPa·s, while, if treated by radiation, it would be greater than 1000mPa·s.

If one coats silicone onto a support, such as paper, polyester oranother material, the surface tension of these supports in general isalways higher than the surface tension of the silicone. The resultingimmediate consequence is that the silicone will wet the surface of thesupport and thus spread on it. Conversely, if one coats silicone on asurface which presents a surface tension which is less than that of thesilicone, such as, for example, a surface which has been treated withfluorine, one will then observe a retraction of the silicone which canlead to dewetting; the liquid film of silicone breaks on the surface ofthe support to form a group of droplets which are separated from eachother. Since it is absolutely necessary to avoid any deformation of thethree-dimensional structure of the silicone when it has just beendeposited on the surface of the support, the surface of the supportideally should have the same surface tension as the silicone which isdeposited on it and thus ideally a surface of the same nature assilicone: a siliconated surface. In this case, the silicone which onecoats will not tend theoretically to retract or spread. Normally, itsstructure will thus remain stable (except for the effect of gravity onthe faces of the three-dimensional structure which will depend to alarge extent on the viscosity of the silicone which one coats. Thehigher it is, the better) in the UV or electronic radiation station,where the microstructured layer of silicone will be definitively fixedby crosslinking. The surface tensions of the silicone layers are 19-24mN/m (or dyne/cm), advantageously 21-23 mN/m. The method which isgenerally used to determine the surface tension is the Owens-Wendt dropmethod with three components (liquids used: hexadecane, water, glycerol,diiodomethane; measurement temperature: 23° C.). One notes that there isvery little difference from the point of surface tension between thesilicone compositions, whether they are treated by the thermal route orby radiation. A layer of silicone which has been treated with heat willhave substantially the same surface tension as a silicone layer whichhas been treated by UV radiation. The microstructured layer of siliconecan consequently be applied easily to the flat surface of a layer ofsilicone which has been crosslinked thermally.

According to the invention, one then deposits the second layer ofsilicone onto the first layer of silicone which then becomes integrallyconnected to thus form a common three-dimensional microstructureensuring anti-adhesive (substrate release) properties which are evenlydistributed on the surface of the support, and onto that siliconizedsupport a liquid solution or paste is deposited which, after drying bythe thermal route, for example, in thermal ovens, or under exposure toUV or electron beam radiation, will form a flexible substrate or filmwhose surface topography is substantially the inverse topography of thatof the three dimensionally microstructured silicone. Indeed, the layersof silicone fulfill a double role; the role of imposing an inversetopography on the surface of a film which will be made in close contactwith them and that of an anti-adhesive agent which will facilitate theseparation of the film made from the material which was applied to themicrostructured silicone. As flexible film to be made, any plastic filmcan be appropriate, for example, cast polyvinyl chloride or a film madeof a solvent base, or in the form of an organosol or plastisol. Othercast films could also be considered, such as polypropylene,polyurethane, and polyethylene. Indeed, the principal objective of themethod of the invention is to confer to the cast film a surface finishby micro-replication, for example, for the visual aspect or for varioustechnical reasons.

According to a particularly advantageous embodiment of the invention,one uses as a substrate a flexible film such as a plastic film, forexample, a polyvinyl chloride film, whose surface is covered with anadhesive, so as to confer to the adhesive a microstructure whichcorresponds to the inverse image of the microstructured silicone. Thelayer of adhesive, in that case, will advantageously be coated directlyon the microstructured silicone, or pressed on the silicone bylamination using a lamination device. During a direct coating, theadhesive will be in liquid form, for example, in solution in an organicsolvent or a mixture of organic solvents or in an emulsion in water, orin the form of a solid, that is in the form of an adhesive withoutsolvent which is hot cast on the microstructured silicone. Since thecoating process used to coat the adhesive on the silicone must be suchthat it does not affect the microstructure of the silicone by abrasion,the latter process is preferably carried out using a slit extruder, acoating roller equipped with a scraper or a doctor bar. As adhesive typeone could use any of the adhesives which are applicable in the fieldconsidered. In this regard, mention is made of the adhesives based onacrylic, rubber, silicone, and polyurethane. These adhesives can besolvent based, water based, or without solvent, in the molten state. Thechoice of the adhesive will determine the ease of replicating themicrostructure of the silicone and the more or less permanentmaintenance of its inverse microstructure when the substrate containingthe microstructured adhesive is later applied to a given object, such asa display window, painted canvas, or a panel. Particularly well suitedare the self adhesive resins which self crosslink when heated, and arebased on an acrylic copolymer dissolved in a mixture of organicsolvents, the self adhesive resins which can be crosslinked by theaddition of isocyanate, and are based on an acrylic copolymer dissolvedin a mixture of organic solvents, the acrylic copolymers in an aqueousdispersion, where the acrylic monomers for this purpose are preferably2-ethylhexyl acrylate, butyl acrylate and acrylic acid, and theadhesives based on natural and/or synthetic rubber, which may or may notbe dissolved in a mixture of organic solvents. These adhesives cancontain one or more additives, such as resins which ensure gluing,antioxidants, plasticizers, fillers, pigments or similar substances.

To clarify the invention, FIG. 1 in the drawing of the appendixrepresents a slightly enlarged cross-sectional view of a support 1 towhich a flat first layer of silicone 2 and microstructured second layerof silicone 3 have been applied, respectively. As one can see, the firstand second layers 2 and 3 and support 1 are adhered together to form aunitary three-dimensional microstructure 4. This microstructure 4comprises a plurality of crests or ridges that consist of themicrostructured layer 3 fixed to support 1 via the first layer 2.Together the first silicone layer 2 and the second silicone layer 3 forma continuous siliconized surface 5 on support 1. The siliconized surface5 has anti-adhesive properties which extend from bottom zones 5 acontinuously over crest zones 5 b to provide a surface adapted torelease a substrate in contact therewith. The plurality of crests orridges are preferably distributed evenly over the siliconized surface 2a of the support 1, and facilitate the separation of a substrate film(see FIG. 7) with or without adhesive which will have been deposited onthe microstructured silicone.

The following tests and examples better illustrate the inventionalthough they in no case limit it.

Tests on a Pilot Installation

The materials used, the operating conditions and the results of thetests are given in Tables 1 and 2 below.

1. Coating of a “Grid” of Silicone on Presiliconated Paper

The coating of the microstructured (“grid shaped”) layer of silicone iscarried out by “inverse” engraving, that is by pyramids on the table ofthe cylinder. These pyramids may have a truncated shape or be similar toa pyramid having its apex removed in a cylindrical fashion.

Characteristics of the engraving (see FIG. 2 a: plan view of theengraving, and FIG. 2 b: cross-sectional view along line 11 b).

Cylinder No. 58472 chrome coated

Depth: 0.050 mm.

Opening: 0.100 mm

Diagonal measurement of the pyramid: 0.500 mm.

Bottom: 0.015 mm.

The filling of the engraving is carried out either using a closedchamber equipped with doctor bars, or by immersion of the engraving inthe silicone bath, where the excess silicone on the surface of theengraving is then eliminated with a doctor bar (made of steel, nylon orany other material). The fixation of the microstructured layer ofsilicone is carried out using a battery of mercury UV lamps with averagepressure and a power of 200 Wm.

TABLE 1 Siliconization (with engraved roller and closed chamber)Pressure Rendering engraving/ Support/ Silicone/ Speed inert with rubbercounter Silicone Test presiliconization catalyst m/min N2 rollerattachment Results (appearance) 1 Signback 13¹⁾ UV902G⁵⁾ 50 <20 ppm O2 2bar Slight peeling Transfer of the silicone R630GE (SS)²⁾ Visco = 800cps* by friction plate, increase the pressure of the engraving/rubbercounter roller 2 Signback 13 VU902G 50 <20 ppm O2 4 bar Slight peelingTotal transfer of the (R630GE (SS) Visco = 800 cps* by friction siliconeplate 3 Signback 13 UV902G 100 <20 ppm O2 4 bar Slight peeling Totaltransfer of the R630GE (SS) Visco = 800 cps* with friction siliconeplate 4 Signback 13 UV902G 50 <20 ppm O2 4 bar Perfect Total transfer ofthe UV902G (+cra Visco = 800 cps* silicone plate 709)³⁾ 5 Signback 13UV902G 50 <20 ppm O2 4 bar Perfect Total transfer of the UV PC900RP⁴⁾Visco = 800 cps* silicone plate 6 Signback 13 UV PC900RP 50 <20 ppm O2 4bar Perfect Total transfer of the UV PC900RP Visco = 1200 cps* siliconeplate

-   -   The Brookfield viscosity of the silicones was measured (spindle        4, speed 20 rpm), unit the centipoise=one mPa·s.

-   1) Signback 13 is a sized paper with kaolin of 130 g/m².

-   2) R630GE (SS) is a mixture of polyorganosiloxanes with Pt catalyst,    without solvent.

-   3) UV902G (+CRA 709) is a mixture of polyorganosiloxanes comprising    acrylate functions, and it is placed in the presence of    2-hydroxy-2-methyl-1-phenylpropanone as photoinitiator, from the    company Goldschmidt.

-   4) UVPC 900 RP is a mixture of polyorganosiloxanes comprising    acrylate functions, and it is placed in the presence of    2-hydroxy-2-methyl-1-phenylpropanone, from the company Rhodia.

-   5) UV 902G is a mixture of polydimethylsiloxanes functionalized with    acrylate function and of 2-hydroxy-2-methyl-1-phenylpropanone from    the company Goldschmidt.

2. Coating of the Adhesive

Formulation of Adhesive Used:

Acrylic copolymer in solution in a mixture of organic solvents: 17 kg.

Butyl acetate (principal solvent): 2.8 kg.

Crosslinking agent: 0.160 kg.

Drying temperature profile: 60° C., 80° C., 100° C., 120° C.

Coating speed: 20 m/min.

Gram weight of the adhesive: 20-25 g/m².

TABLE 2 Coating of the adhesive Example Results No. Adhesive Face(appearance) 1 Acrylic copolymer in M8129¹⁾ Acceptable spreading ofsolvent the adhesive 2 Acrylic copolymer in M8129 Good spreading of thesolvent adhesive 3 Acrylic copolymer in M8129 Good spreading of thesolvent adhesive 4 Acrylic copolymer in M8129 Acceptable spreading ofsolvent the adhesive ¹⁾M8129 is a sheet of glossy white PVC having athickness 90 μm.

One can thus see that the coating of a silicone relief via so-calledinverse engraving yields excellent results.

FIG. 3 is a scanning electron micrograph of the microstructured surfaceof silicone of Example No. 2 according to the invention (magnification×15 and ×30).

FIG. 4 is a scanning electron micrograph of the microstructured surfaceof silicone obtained by a known method of the prior art.

According to this known method, the layer of silicone, deposited on theglossy face of the polyethylene film of a two-faced polyethylenatedpaper, is microembossed with heating (110° C.) and at low speed (0.9m/min) by an engraved cylinder; the counter cylinder is a siliconerubber roller which has a Shore hardness of 85 and is heated at 120° C.;the pressure exerted between the two cylinders is 22 N/mm².

As one can note, the inventive microstructured support has on thesurface of the silicone (FIG. 3) very regular features which are roundedat the level of the crests, which prevents or reduces the possibility oftransfer of the image of the silicone pattern to the surface of thesubstrate e.g. a flexible film of PVC, that is there is no alteration inthe surface appearance of the substrate film. This is not the case withthe micro-honeycombs of FIG. 4, where the surface of the substrate PVCfilm is altered by the microstructures of the polyethylenated andsiliconated paper whose embossed crests are much sharper and lessrounded; the micro-honeycombed pattern is visible through the PVC filmwhich the crests deform. To ameliorate this pattern transfer through tothe substrate, the prior art may use a thicker substrate to lessen orblunt the image transfer. Advantageously, preferred embodiments of thepresent invention use rounded microstructured crests or ridges whichlessen or prevent silicone crest pattern transfer through to asubstrates distal surface. Thus, the microstructured support of thepresent invention may by inverse replication define the topography ofthe adjacent proximate surface of the substrate while not transferring avisible (to the naked eye) image through to the distal surface of thesubstrate. This means that use of thinner substrates or facestocks maybe possible e.g. 60 ìm, 50ìm, or 40 ìm or less may possibly be usedthereby effecting a material cost savings since it is unnecessary to usean added thickness to lessen the visual effect caused by using apatterned silicone liner having sharp crests.

Other tests and test results are given in Tables 3 and 4 below.

1. Coating of a Grid of Silicone on Presiliconated Paper

The operating procedure is substantially the same as the one used above.

TABLE 3 Siliconization (with engraved roller and doctor bar) Support/Silicone/ Speed Rendering Pressure engraving/ Silicone Results Testpresiliconization catalyst m/min inert with N2 rubber counter rollerattachment (appearance) 1 Signback 13 UV902G 50 <20 ppm O2 4 bar Slightpeeling Total transfer of R630GE (SS) by friction the silicone plate 2Signback 13 VU902G 50 <20 ppm O2 4 bar Slight peeling Total transfer ofUV902G by friction the silicone plate 3 Signback 13 UV902G 50 <20 ppm O24 bar Perfect Total transfer of UV PC900RP the silicone plate 4 PET 29μtreated UV902G 50 <20 ppm O2 4 bar Slight peeling Total transfer of RF310 RP (1, 6) by friction the silicone plate R630RP: mixture ofpolyorganosiloxanes without solvent from Rhodia RF310RP: mixture ofpolyorganosiloxanes without solvent from Rhodia UV902G: see Table 1(viscosity 800 cps, spindle 4, v20). UV PC900RP: see Table 1

2. Coating of the Adhesive

Formulations of Adhesive Used:

-   -   1. MP 500 (Solucryl 340: acrylic copolymer in solution in a        mixture of organic solvents).        -   Gram weight: 24.5 g/m²        -   Viscosity: 135 cps (spindle 4, v20, Brookfield)        -   Drying temperature profile: 70° C., 90° C., 110° C., 140° C.        -   Coating speed: 10 m/min.    -   2. MR 980 (Solucryl 615: acrylic copolymer in solution in a        mixture of organic solvents).        -   Gram weight: 16 g/m²        -   Viscosity: 790 cps (spindle 4, v20, Brookfield)        -   Drying temperature profile: 70° C., 90° C., 110° C., 190° C.        -   Coating speed: 20 m/min.

TABLE 4 Coating of the adhesive Presiliconated Results Example No. paperSilicone Adhesive Face (appearance) Reference A SIGNBACK 13 / MP500M9829 Good coating of UV PC900RP polymer 75μ the adhesive  5 SIGNBACK 13UV902G MP500 M9829 Good coating of R630GE (SS) the adhesive, a fewbubbles  6 SIGNBACK 13 UV902G MP500 M9829 Good coating of UV PC902G theadhesive, very few bubbles  7 SIGNBACK 13 UV902G MP500 M9829 Goodcoating of UV PC900RP the adhesive, a few bubbles  8 SIGNBACK 13 UV902GMP500 M2629 Good coating of UV PC900RP polymer 60μ the adhesive, a fewbubbles  9 SIGNBACK 13 UV902G MP500 M2629 Good coating of R630GE (SS)the adhesive, a few bubbles 10 SIGNBACK 13 UV902G MP500 M2629 Goodcoating of UV902G the adhesive, very few bubbles 11 PET 28μ treatedUV902G MP500 BOPP 58μ Good coating of RF310RP (1, 6) clear the adhesive,very few bubbles Reference B SIGNBACK 13 / MP500 M2629 Good coating ofUV PC900RP the adhesive Reference C SIGNBACK 13 / MR980 M2629 Goodcoating of UV PC900RP the adhesive 12 SIGNBACK 13 UV902G M2629 Goodcoating of R630GE (SS) the adhesive, very few bubbles 13 UV902G UV902GMR980 M2629 Perfect coating of the adhesive, no bubbles 14 SIGNBACK 13UV902G MR980 M2629 Good coating of UV PC900RP the adhesive, very fewbubbles 15 SIGNBACK 13 UV902G MR980 M9829 Good coating of UV PC900RP theadhesive, very few bubbles 16 SIGNBACK 13 UV902G MR980 M9829 Goodcoating of R630GE (SS) the adhesive, very few bubbles 17 SIGNBACK 13UV902G MR980 M9829 Perfect coating of UV902G the adhesive, no bubblesReference D SIGNBACK 13 / MR980 M9829 Good coating of UV PC900RP theadhesive

One notes that even with a very thin substrate facestock (face) offlexible PVC film of 60 μm thickness (M2629), one does not see thesilicone pattern image transferring through.

Tests of Industrial Application

1. Coating of Silicone with “Inverse” Engraving, and Polyester DoctorBar.

The material used, the operating conditions and the results of the testsare given in Table 5 below.

The coating of the microstructured layer of silicone is thus carried outby inverse engraving, that is by pyramids on the table of the cylinder.

Characteristics of the Engraving:

Cylinder chrome coated Depth 0.050 mm Width 530 mm Opening 0.100 mmDiagonal measurment 0.500 mm of the pyramid Bottom 0.015 mm

The fixation of the microstructured layer of silicone is carried out byusing 2 Hg arc-lamps with a power of 120 W/cm under an inertingatmosphere of N₂ (<20 ppm of O₂).

TABLE 5 Siliconization with engraved roller and polyester doctor barPresure Sized paper Rendering engraving/ Adhesive Silicone 130 g/m²Speed inert with rubber counter Silicone Results Test Face (slot die)(gravure) presiliconized m/min N2 roller attachment (appearance) 1 PVCcast MP673HR / Silicone 40 / / perfect / (contol) black 50 μm 34 g/m²R625DC (0.9 g/m²) 2 PVC cast MP673HR UV902G Silicone 40 <20 ppm O₂ 4bars perfect Total transfer of the blue 50 μm 34 g/m²   8 g/m² R620DC(0.9 g/m²) silicone plate 3 PVC white MP673HR UV902G Silicone 40 <20 ppmO₂ 4 bars perfect Total transfer of the 60 μm 34 g/m²  10 g/m² R620DC(0.9 g/m²) silicone plate 4 PVC white MP673HR UV902G Silicone 40 <20 ppmO₂ 4 bars perfect Total transfer of the 60 μm 34 g/m² 6.8 g/m² R620DC(0.9 g/m²) silicone plate R625DC/R620DC = Silicone system withoutsolvent from Dow Corning. UV902G = UV free radical crosslinking siliconesystem from Goldschmidt (viscosity brookfield 800 cps, spindle 4, speed20 tours/min).

2. Coating of the Adhesive

Formulation of adhesive used: Resin Solucryl 360 AB (acrylic copolymer);720 kg Solvent Butyl acetate; 150 kg Crosslinking mixture of2-pentanedione (1.5 kg), 3-isopropanol agent (0.8 kg), Ti acetylacetonate (0.188 kg) and Al acetyl acetonate (2.02 kg). Viscosity 1300cps (spindle 4, v20, brookfield).

One . . . can thus see from Table 6 that like in the case of the testson pilot installation the coating is carried out under excellentconditions, the adhesive performances and anti-adhesive values beingsubstantially lower than those obtained with control test.

TABLE 6 Coating of the adhesive (appearance and characteristics)Adhesive performances Anti-adhesive values Peeling FTM3 inox plateImmediate adhesion 300 mm/min FTM4 Appearance of (N/inch) inox platePeeling off, face 10 m/min Test the adhesive 24 h 1 week (N/inch) N/2inches g/2 inches 1 good coating 17.9 20.59 15.65 0.56 64.2 (control) 2good coating 13.11 15.45 12.05 0.18 20.4 3 good coating 14.38 15.2814.85 0.24 32.2 4 good coating 13.61 15.48 13.83 0.27 33

FIG. 5 is a scanning electron micrograph of the microstructured surfaceof silicone (top left side) and of an inversely replicated adhesive(bottom right side) obtained according to the method of the invention onindustrial application (60× magnification with a 68° tilt).

Like in the case of the tests on pilot installation one can note thatthe microstructured crests are very smooth and the conjunction ofrounded crests and of relatively small crest depth of about 10 μm,cooperates to greatly reduce and even prevent the visible transfer ofthe microstructured silicone pattern to the distal surface of theadhesive coated substrate of the flexible film of PVC. Advantageously,crest or ridge depths less than 15 μm may be used to help lessen orprevent the undesirable visual effect.

FIG. 6 is a scanning electron micrograph of the initial contacttopography between the adhesive surface and the surface of the substratesupport which receives the self-adhesive film microstructured accordingto the method of the invention. As one can clearly note from thismicrograph, and more particularly from the plate crest bordered anddivided into four squares of the same surface, the percentage of initialcontact area may be made substantially lower than the values obtainedwith the microstructured adhesives known to date, which are higher than35%. Here, the contact area is about 25%. Depending on the appearance ofthe adhesives used, the composition thereof and the processingconditions, the percentages of initial contact surface between theadhesive layer and the substrate support may vary and in one preferredembodiment are from 15 to 32%, and preferably of 23 to 28% of the totalcovering surface. In these preferred embodiments this low level ofcontact surface allows for better repositioning properties of theadhesive film than the adhesive films of the prior art, in conjunctionwith good adhesion between the surface of the substrate and a supportingobject to which it is applied, because the adhesive surface at the topof the crests is substantially planar and will give by microreplicationa plane microplateau. Furthermore, the presence of so formedmicrochannels of small depth (of about 10 μm) and the high immediate noncontact adhesive surface (of about 70% or more) provides to theself-adhesive product a repositionable character in the case of theinitial application pressure is low. Now, if a higher pressure isexerted upon the applied adhesive film, said film is immediately fixedto the surface of a supporting object because all the planar surfaces ofthe crests of adhesive in the form of plane plateaux are then in fullcontact with the object surface. The microchannels formed by theadhesive contact with the object surface and circumscribed by the objectsurface and the substrate's immediate non contact adhesive surfaces havea depth which allows an easy egress and elimination of the pockets ofair which could occur at the interface of adhesion during theapplication of the self-adhesive product. The simple contact of the handon the locations where the pockets of air are formed can cause the rapidand complete suppression or expulsion of these pockets of air. If agreater pressure is then exerted, the plane surfaces of the differentplateaux of adhesive can extend substantially to the plane valleys ofthe first layer of silicone depending on the exerted pressure, theviscoelasticity properties of the adhesive, the time and the temperatureto coalesce into a uniform and continuous surface (without the originalmicrochannels) in close contact with the application (object).

FIG. 7 is a diagrammatic representation in two dimensions of the processof the invention showing a presiliconised support (1, 2) on which amicrostructured silicone layer 3 has been applied, hardenable byultraviolet radiation, as well as an inverse replicatedthree-dimensional microstructure obtained on the adhesive layer 10 ofsubstrate 11 when contacting the latter with the presiliconized liner(1,2) and the microstructured layer 3, and also a substrate 11 having afacestock 12.

As shown, one can note that the percentage of adhesive surface whichwill be immediately in contact with the surface on which theself-adhesive film will be applied is 27%, this percentage beingcalculated as follows:

Distance  AB = 237  µm Distance  BC = 216  µm${s/S} = {\frac{237^{2}}{\left( {237 + 216} \right)^{2}} = 0.27}$

It should be also noted that the adhesion interface between the adhesivesurface and the application surface is substantially planar because itcorresponds to the valleys formed by the first flat layer of silicone ofthe three-dimensional microstructure.

Besides the already detailed advantage that one may obtain amicrostructured surface of silicone on any type of substrate, such as acellulosic or noncellulosic paper (calendered or glossy, sized), plasticfilms e.g. polyester, polyolefin, polyethylene, polypropylene, polyamide(uniaxially or biaxially oriented or unoriented, monolayer ormultilayer, with or without printing or designs, colorants, processingaids, fillers and the commonly known additives) and the advantage thatone can coat the silicone on a support web at a very high speed e.ggreater than 10 meters/minute(m/min), and preferably greater than 50 andeven 300 m/min, the principal advantages of the microstructuring methodof the invention are that one may obtain extremely regularmicrostructured motifs whose crests may be configured (e.g. small heightand rounded) so as to not deform the substrate film (or facestock) onwhich the microreplicated surface of adhesive is applied.

The principal use of a microstructured adhesive is that it makes it easyto apply, for example, large emblems on given surfaces. Indeed, ingeneral one has to remove and reapply the emblem to position it betterand, once it is applied, one often has to eliminate pockets of aircaught under the self-adhesive film during the application or pockets ofgas which occur sometime after the application. The microstructuredadhesive according to the present invention allows easy repositioning,easy elimination of bubbles during the application by simply applyingmanual pressure e.g. with one or more fingers or a hand, and it allowsthe elimination, through the microchannels formed, of any gas which mayhave been enclosed after the application.

It will be apparent from the foregoing that various inventive articlesmay be formed according to the present invention including a novelrelease liner, a novel pressure sensitive adhesive label having arelease liner and that such articles may be employed in a wide varietyof applications including in the production of very large graphic panelssuitable for placement on buildings, vehicles and billboards. Such largegraphic panels may have a width of 30, 50, 100 or 150 cm or more with alength usually at least as long or often 1, 2, 3 or many meters more inlength. Such panels or sheets may often have a thickness of 1.25millimeters(mm) or less.

One preferred embodiment of the invention is a multilayer sheetcomprising:

(a) a flexible support comprising:

(i) a sheetlike structure having a first broad surface and opposingsecond broad surface;

(ii) a first layer of a silicone containing material e.g. in a sheetlikecoating that is fixed to at least the first broad surface of theaforementioned sheetlike structure; (iii) a second layer of a siliconecontaining material fixed to the first layer (ii) as a plurality ofridges or crests thereby providing a flexible support having on at leastone broad surface thereof a three dimensional topography of a pluralityof ridges or crests; and

(b) a flexible substrate having a proximate first surface and opposingdistal second surface wherein the proximate first surface is inreleasable contact with the three dimensional surface of the flexiblesupport and the proximate first surface has a mating inverselyreplicated three dimensional topography.

The sheetlike structure of the flexible support is preferably notdistorted into a plurality of ridges or crests corresponding to thesecond layer ridges or crests e.g. by embossing. Advantageously, thedistal second surface of the flexible substrate is visually free fromany ridge or crest pattern corresponding to the plurality of ridges orcrests of the flexible support. The substrate may comprise a firstadhesive layer forming a proximate first surface of the substrate andmay optionally further comprise a first facestock layer in contact withthe first adhesive layer and the facestock layer forming an opposingdistal second surface of the substrate. The distal substrate surface maybe printed e.g. using inks, pigments or colorants, with one or moreimages, indicia or designs or it may be unprinted, transparent, opaque,translucent, black, white or colored, either in part or over its entiresurface. The distal surface of the substrate may also optionally have anadditional exterior protective coating or layer applied thereto.

It should be understood that the invention is in no way limited to thedescribed embodiments and that many modifications can be made to thelatter without exceeding the context of the present patent.

1. Method of forming a three-dimensional microstructure on a flatsurface of a support, characterized in that it comprises the applicationof a first flat and uniform layer of silicone on said surface of supportand the application on the first layer of silicone of a second threedimensionally microstructured layer of silicone, said first layer andsecond layer of silicone become integrally connected to thus form acommon three-dimensional microstructure ensuring anti-adhesiveproperties distributed regularly on the surface of the support, so thatany flexible surface of substrate, in particular a surface of adhesivedeposited on said layers of silicone will be microstructured by inversereplication of the three-dimensional microstructure formed by the twolayers of silicone, where said layers of silicone are fixed by hardeningby heating or by exposure to an ultraviolet or electronic radiation, ora combination thereof.
 2. Method for the three-dimensionalmicrostructuring of a flexible surface of substrate, in particular asurface of adhesive, characterized in that it comprises the applicationof a first flat and uniform layer of silicone on a surface of a support,the application on the first layer of silicone of a second threedimensionally microstructured layer of silicone, where said first layerof silicone and second layer of silicone become integrally connected tothus form a common three-dimensional microstructure ensuringanti-adhesive properties distributed regularly on the surface of thesupport, and the deposition of the flexible surface of substrate, inparticular of the surface of adhesive on said layers of silicone so thatsaid flexible surface of substrate, in particular of adhesive, ismicrostructured by inverse replication of the common three-dimensionalmicrostructure formed by the first layer of silicone and the secondlayer of silicone, where said layers of silicone are fixed by hardeningby heating or by exposure to an ultraviolet or electronic radiation, ora combination thereof.
 3. Method according to either one of claims 1 and2, characterized in that the three-dimensional microstructure formed bythe first layer and second layer of silicone comprises micro-honeycombedmotifs.
 4. Method according to any one of claims 1-3, characterized inthat one three dimensionally microstructures a surface of adhesive. 5.Method according to any one of claims 1-4, characterized in that thefirst layer of silicone comprises a functionalized polyorganosiloxanewith groups

as crosslinking agent, and at least one functionalizedpolyorganosiloxane which can react with the crosslinking agent. 6.Method according to any one of claims 1-4, characterized in that thefirst layer of silicone comprises a functionalized polyorganosiloxanewith groups

as crosslinking agent, and at least one functionalizedpolyorganosiloxane with groups

which can react with the crosslinking agent, where R comprises at leastone ethylenic unsaturation.
 7. Method according to either one of claims5 and 6, characterized in that the first layer of silicone comprises acatalyst for the activation of said crosslinking reaction.
 8. Methodaccording to claim 7, characterized in that the activation catalyst isselected from the platinum, rhodium or tin based catalysts.
 9. Methodaccording to any one of claims 5-8, characterized in that the firstlayer of silicone comprises, in addition, one or more additives chosenfrom the group comprising the adhesion modulators, the reactionaccelerators and inhibitors, the pigments, the surfactants and thefillers.
 10. Method according to any one of claims 7-9, characterized inthat the first layer of silicone is hardened by heating or by exposureto an ultraviolet radiation.
 11. Method according to claim 10,characterized in that, when the layer of silicone is hardened byheating, it is heated at temperatures of 70-200° C., advantageously100-180° C.
 12. Method according to either one of claims 5 and 6,characterized in that the first layer of silicone is hardened byexposure to electronic radiation.
 13. Method according to any one ofclaims 5-12, characterized in that the first layer of silicone has athickness of 0.4-1.6 μm, advantageously 0.7-1.2 μm.
 14. Method accordingto any one of claims 1-13, characterized in that said second layer ofsilicone comprises at least one polyorganosiloxane, advantageously apolydimethylsiloxane with acrylate function, and a catalyst of theketone type, advantageously of the benzophenone type, and it is hardenedby exposure to ultraviolet radiation.
 15. Method according to any one ofclaims 1-13, characterized in that said second layer of siliconecomprises at least one polyorganosiloxane, advantageously apolydimethylsiloxane with epoxy function, and a catalyst of the iodoniumsalt type, and it is hardened by exposure to ultraviolet radiation. 16.Method according to any one of claims 1-13, characterized in that saidsecond layer of silicone comprises at least one polyorganosiloxane,advantageously a polydimethylsiloxane with acrylate and/or epoxyfunction, and it is hardened by exposure to ultraviolet radiation(acrylate and/or epoxy function) or electronic radiation (acrylatefunction).
 17. Method according to any one of claims 3-16, characterizedin that the three-dimensional microstructure formed by said first layerof silicone and said second layer of silicone consists of microembossedmotifs, whose crest height varies from 3 to 50 μm, advantageously from 5to 25 μm.
 18. Method according to any one of claims 1-17, characterizedin that the second layer of silicone is applied to the first layer in aquantity which can range from 3 to 25 g/m², advantageously from 4 to 15g/m².
 19. Method according to any one of claims 1-18, characterized inthat the first layer of silicone and the second layer of silicone havesurface tensions which are close to each other, from 15 to 25 mN/m,advantageously from 21 to 23 mN/m.
 20. Method according to any one ofclaims 1-19, characterized in that said substrate and support consist ofpaper, notably calendered or sized paper, a plastic film, notably madeof polyethylene, polyester, polypropylene, polyvinyl chloride,polyamide.
 21. Method according to any one of claims 4-20, characterizedin that said adhesive is deposited on said first layer and second layerof silicone either by coating directly on said layers or by lamination.22. Method according to claim 20, characterized in that, in the case ofdirect coating, the adhesive is either in liquid form, advantageously inan organic solvent or in an emulsion in water, or in a hot cast solidform.
 23. Method according to any one of claims 4-22, characterized inthat the adhesive is applied to a flexible plastic film, advantageouslya film of polyvinyl chloride.
 24. Method according to any one of claims2-23, characterized in that during the application of said adhesivesurface on any surface, the adhesive surface contact with the latter isfrom 15 to 32%, preferably 23 to 28% of the total covering surface. 25.Three dimensionally microstructured film, and/or self-adhesive filmcomprising a surface of adhesive such as one which is threedimensionally microstructured by the method according to any one ofclaims 1-23 and comprises notably motifs for decorative, publicity orother purposes on the surface opposite the surface which is in contactwith the microstructure formed by said layers of silicone.
 26. Amultilayer sheet comprising: (a) a flexible support comprising: (i) asheetlike structure having a first broad surface and opposing secondbroad surface; (ii) a first layer of a silicone containing material in asheetlike coating that is fixed to at least said first broad surface ofsaid aforementioned sheetlike structure; (iii) a second layer of asilicone containing material fixed to said first layer (ii) as aplurality of ridges thereby providing a flexible support having on atleast one broad surface thereof a three dimensional topography of aplurality of ridges; and (b) a flexible substrate having a proximatefirst surface and opposing distal second surface wherein said proximatefirst surface is in releasable contact with said three dimensionalsurface of said flexible support and said proximate first surface have amating inversely replicated three dimensional topography.
 27. Amultilayer sheet, as defined in claim 26, wherein said sheetlikestructure of said flexible support is not distorted into a plurality ofridges corresponding to said second layer ridges by embossing.
 28. Amultilayer sheet, as defined in claim 26, wherein said distal secondsurface of said flexible substrate is visually free from any ridgepattern corresponding to said plurality of ridges of said flexiblesupport.
 29. A multilayer sheet, as defined in claim 26, wherein saidsubstrate comprises a first adhesive layer forming a proximate firstsurface of said substrate.
 30. A multilayer sheet, as defined in claim29, wherein said substrate further comprises a first facestock layer incontact with said first adhesive layer and said facestock layer forms anopposing distal second surface of said substrate.
 31. A multilayersheet, as defined in claim 26, wherein said distal second surface ofsaid substrate has an additional exterior layer applied thereto.
 32. Amultilayer sheet, as defined in claim 26, wherein said distal secondsurface of said substrate is printed with at least one image.